This invention relates in general to conveyor unloading apparatus and deals more particularly with improved apparatus for unloading sheet material from a belt conveyor or the like. The apparatus of the present invention is particularly adapted for use with a conveyorized machine for working on sheet material wherein the machine conveyor includes a penetrable sheet material support surface defined by terminal ends of a multiplicity of upstanding elements, such as bristles, upon which a single sheet or a layup of sheet material comprising a plurality of sheets arranged in vertically stacked relationship may be supported while being cut or otherwise worked upon by a tool which may pass through the sheet material and penetrate the support surface.
Machines of the aforedescribed general type are used to cut woven or non-woven fabrics, synthetics, plastics, paper, leather and other materials and usually include a vacuum system for compressing a layup of material and holding it in firmly fixed position on the support surface of the conveyor while a tool moves in working relation to it in response to command signals received from a programmable controller. An apron is usually located at the discharge or return end of the machine conveyor to provide transition between the conveyor support surface and the surface of an adjacent receiving table. The conveyor moves the layup across the apron and onto the receiving table upon completion of the working cycle of the machine.
In a machine of the aforedescribed type, problems are sometimes encountered in conveying the layup to the receiving table. The weight of the layup may, for example, cause the leading edge or edges of the lowermost layer or layers of the layup to catch upon the lip of the apron and be deflected downwardly by the lip to follow the return portion of the belt conveyor. When such a machine is used to cut a woven fabric, a further problem may be encountered. As the cutting blade passes through the lowermost layers of the fabric some of the cut weave threads adjacent the blade may be forced downwardly between the closely packed bristles which define the support surface. Since vacuum is applied to the lower surface of the layup during the cutting operation, there is a further tendency for such cut thread ends to be drawn downwardly between the bristles and become lodged therebetween. This condition further contributes to the aforedescribed problem. The present invention is concerned with these problems.